Display screen or portion thereof with a graphical user interface



The FIGURE is a front view of a display screen or portion thereof with agraphical user interface.

The dot-dot broken line shown in the drawing forms a part of the claimeddesign. The dash-dash broken lines and the broken line text shown in thedrawing illustrate a device and/or portions of the display screen orportion thereof with a graphical user interface that form no part of theclaimed design.

CLAIM The ornamental design for a display screen or portion thereof witha graphical user interface, as shown and described.